Supplemental information - Narrative (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Nov. 30, 2020	Nov. 30, 2019	Aug. 31, 2020
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable from related party	$ 1,200		$ 1,200
Accumulated depreciation and amortization on property, plant, and equipment	12,700		12,500
Restricted cash (included in other current assets)	228		230
Redeemable noncontrolling interest	178		0
Cumulative translation adjustments	$ 3
Antidilutive securities excluded from EPS calculations (in shares)	18.5	16.7
Incremental antidilutive securities excluded from EPS calculations (in shares)	0.5
Trade Accounts Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Receivables	$ 6,600		$ 6,000